The present invention relates to lift vehicles such as aerial work platform vehicles, telescopic handlers, and the like and, more particularly, to a lift vehicle including a multiple capacity system with multiple envelope control.
Boom lift vehicles are known that include a tower boom pivotally coupled to a vehicle base, and a main boom pivotally coupled to an opposite end of the tower boom. One or both of the tower boom and the main boom may also be capable of expansion and retraction via telescope sections. A jib arm may be pivotally attached at an end of the main boom to support an aerial work platform.
Existing lift vehicles typically define a safe operating envelope for positioning the aerial work platform relative to the vehicle base. The envelope is conventionally determined based on a maximum load capacity of the aerial work platform. As a consequence, when the aerial work platform supports a collective mass lower than the maximum load, safe operating positions of the aerial work platform may in fact extend beyond the envelope. As a consequence, when the aerial work platform supports a reduced load, the vehicle is not being used to its full capabilities.
JLG Inc.'s 1350SJP utilized a dual capacity “control” system in which the envelope was automatically limited by the control system to stay within selectable envelopes. The previous method was purely an “indication” system in which the envelope was indicated to the operator who had the responsibility to prevent the boom from leaving the envelope matching the desired capacity. The 1350SJP had, as a part of the primary control system, “infinite” length and “infinite” angle measuring sensors necessary to determine the position of the boom within the envelope, as none of the envelopes could be bounded by mechanical limits. The known “infinite” lengths and angles were used to redefine the shape of the envelope for the restricted capacity envelope. The 1350SJP used “controlled arc” to automatically navigate the envelope edges in the same way for both capacities. Other than reducing the envelope size and restricting the functionality of the side swing jib, the machine worked the same regardless of the capacity mode selection.